1. Field of the Invention
The present invention relates to a refrigerated food storage apparatus and, more particularly, to a structure of an outer wall or hinged door of such an apparatus, in which a plurality of integrally formed bosses are provided on an inner panel or panels of the structure, to extend outward within an inter-panel space filled with an insulating body by a reactive foam injection process.
2. Discussion of the Related Art
A food storage apparatus, commonly known as a refrigerator or freezer, generally includes an insulated interior cabinet formed by five outer walls and at least one hinged door provided on a side or top surface. The outer walls and door are essentially comprised of a combination of inner and outer panels which are spaced apart from each other using a spacing means connected to the outer panel, thereby forming an inter-panel space. A body of insulation, e.g., Styrofoam, is injected into the inter-panel space using a foam injection process, to completely fill the space. Thus, the interior cabinet is thermally insulated for the storage of perishable foodstuffs and the like. The food storage apparatus is designed such that, once the air in the interior cabinet is refrigerated (or heated) to a desired temperature, the temperature is maintained by insulating the cabinet's interior from its exterior and blocking the effluence of the temperature-controlled air. Generally speaking, the design and structure of the door of the apparatus has a greater affect on this operation than the outer walls.
Specifically, the spacing means is integrally formed with the outer panel (shell), which forms the exterior shape of such a food storage apparatus and is generally made of a plastic material. The inner panel (liner) forms the shape of the interior cabinet and is also typically made of plastic. The panels are combined to form an outer wall or door using a conventional coupling means.
In the structure of the insulated outer wall or door as described above, the spacing means is realized by a plurality of bosses (spacers) integrally formed with the outer panel, to support the combination of the panels and maintain a constant panel separation distance which defines the inter-panel space. The bosses are provided at regular intervals on the inner side of the outer panel, to extend inward, by a molding process using heat. Therefore, one end (bottom) of the boss is common with the outer panel forming the visible exterior of the food storage apparatus. After the molding process, the bosses are cooled and a contraction takes place at the bottom of each boss, forming a series of slight depressions in the outer panel. Such imperfections in the exterior surface of a food storage apparatus detract from its appearance, by producing an uneven surface considered unsightly.
The foam injection process is conventionally performed with the workpiece (e.g., door) situated horizontally while the space between the door's outer and inner panels is filled with the foam. To ensure a closely coupled fit during foam injection, the inner and outer panels are held tightly together using an auxiliary support means. The door is then left undisturbed for a predetermined time to allow the foam to set. The horizontal orientation of the door leads to difficulties in achieving an even consistency of the filled foam throughout the inter-panel space, whereby the foam fills the space insufficiently and/or disproportionally and the insulation efficiency is thereby degraded. The foam injection process also generates gases which transform an unshaped body of the foam insulation, i.e., before setting, so that the foam injected first and pushed to the rear of the inter-panel space with continued injection bears the pressure of the generated gases. Besides a further hindrance to achieving a consistently filled inter-panel space, the pressure of the generated gases has the potential to buckle one or the other of the panels.
After completing the foam injection process, the surface of the outer panel is finished. That is, the outer panel is generally provided with a foam injection hole for introducing the foam into the inter-panel space. The foam injection hole is sealed to prevent foreign matter from entering the inter-panel space and is then finished (smoothed) to achieve an attractive appearance. The finishing process of the foam injection hole is time consuming and difficult. More importantly, however, even a well-finished hole is unsightly and detracts from the appearance of the food storage apparatus.